In spite of the apparent importance of social integration for work collec- tives within organizations, information systems researchers have so far paid little, if any, attention to evaluating its role in system development projects. The present study tries to contribute to the literature by proposing and testing a model that examines some of the antecedents and consequences of social integration in sys- tem development projects. Data collected from system development project lead- ers working in 84 US organizations were used to test the model. The findings suggest that higher social integration and, consequently, higher system develop- ment project performance is best attained when management provides basic sup- port for the work of the project. The results also reveal that the nature of the relationship between social integration and project performance may be contingent upon some other factors. The implications of the findings of this research are discussed.